Hepatic. Ascorbic acid is reversibly oxidised (by removal of the hydrogen from the enediol group of ascorbic acid) to dehydroascorbic acid. The two forms found in body fluids are physiologically active. Some ascorbic acid is metabolized to inactive compounds including ascorbic acid-2-sulfate and oxalic acid.
来源:DrugBank
代谢
抗坏血酸-2-硫酸盐已经被识别为人尿中维生素C的代谢物。
Ascorbic acid-2-sulfate has ... been identified as metabolite of Vitamin C in human urine.
Ascorbate is oxidized to CO2 in rats and guinea pigs, but considerably less conversion can be detected in man. One route of metabolism of the vitamin in man involves its conversion to oxalate and eventual excretion in the urine; dehydroascorbate is presumably an intermediate.
... Young male guinea pigs /were fed/ diets containing either 2 g/kg (18 control animals) or 86 g/kg (29 treatment animals) of ascorbic acid for 275 days. The average weight gain was significantly higher in the control group. Eight control and eight treatment animals, chosen to maintain comparable weights between the groups, were then given a totally deficient ascorbic acid diet 24 hr before a metabolic study was initiated. In the metabolic study, (14)C-labeled L-ascorbic acid (628 g) was then injected intraperitoneally into both treatment and control guinea pigs to study the catabolism and excretion of the ascorbic acid. Catabolism of the labeled ascorbic acid to respiratory (14)CO2 was increased in treatment guinea pigs. The control and treatment animals were then divided into two groups. One group received 3 mg/kg ascorbic acid (chronic deficiency) for 68 days. The other received a diet devoid of ascorbic acid (acute deficiency) for 44 days. Four control and three treatment animals from the chronic deficiency group and three control and four treatment animals from the acute deficiency group were given a totally deficient ascorbic acid diet 24 hr before a second metabolic study was initiated. (14)C-labeled L-ascorbic acid (628 g) was injected intraperitoneally as above. Treatment animals in the chronic deficiency and the acute deficiency groups had increased catabolism of the labeled ascorbic acid to respiratory (14)CO2 compared to control animals in the chronic and acute deficiency groups. The amount of radioactivity recovered in the urine and feces was similar for both groups except for an increased urinary excretion of the label in treated animals exposed to the totally deficient diet. The treatment animals maintained higher tissue stores of ascorbic acid than the control animals. However, this difference was significant only in the testes. When subjected to a totally deficient diet the treatment animals were depleted of ascorbic acid at a faster rate than the control animals. The accelerated catabolism was not reversible by subnormal intakes of the vitamin ...
... Hartley guinea pigs approximately 30 days pregnant /were divided/ into a control group receiving 25 mg ascorbic acid and a treated group receiving 300 mg/kg/day ascorbic acid daily. All animals were fed a 0.05% ascorbic acid diet. The groups were maintained for 10 days on their respective diets. Pups (both sexes) were randomly chosen on either day 5 or day 10 for the metabolic study. L-l-(14)C-Ascorbic Acid (10 uCi/mM) was injected intraperitoneally into the pups and they were placed in a metabolic chamber for five hours to collect expired (14)CO2. From day 11 all pups were caged individually and weaned to a diet containing only traces of ascorbic acid. Every third day the animals were examined for physical signs of scurvy. Once signs appeared, the animals were examined daily until death. Necropsies were performed on all animals. Pups from the treated group demonstrated a marked increase in (14)CO2 excretion following the intraperitoneal injection. Signs of scurvy appeared 4 days earlier in the treated group and mortality of the treated pups occurred approximately one week earlier. When excretion of labeled CO2 in both groups was correlated with the day of onset of scurvy signs, a linear correlation was found between the two parameters, suggesting that the earlier appearance of signs of scurvy on the experimental pups is secondary to an increased rate of ascorbic acid catabolism ...
IDENTIFICATION: Origin of the substance: Ascorbic acid is of both natural and synthetic origin. Natural origin: ascorbic acid is found in fresh fruit and vegetables. Citrus fruits are a particularly good source of ascorbic acid and also hip berries, acerola and fresh tea leaves. Ascorbic acid exists as colorless, or white or almost white crystals. It is odorless or almost odorless. It has a pleasant, sharp acidic taste. It is freely soluble in water and sparingly soluble in ethanol. It is practically insoluble in ether and chloroform. HUMAN EXPOSURE: Main risks and target organs: The main target organs for toxicity are found in the gastrointestinal, renal and hematological systems. Summary of clinical effects: In individuals with glucose-6-phosphate dehydrogenase (G-6-PD) deficiency, hemolytic anemia may develop after administration of ascorbic acid. In individuals predisposed to renal stones, chronic administration of high doses may lead to renal calculi formation. In some cases, acute renal failure may be observed under both conditions. Indications: Prevention and treatment of scurvy. It has been used as a urinary acidifier and in correcting tyrosinemia in premature infants on high-protein diets. The drug may be useful to treat idiopathic methemoglobinemia. Contraindications: Ascorbic acid is contraindicated in patients with hyperoxaluria and G-6-PD deficiency. Routes of entry: Oral: Ascorbic acid is usually administered orally in extended-release capsule form, tablets, lozenges, chewable tablets, solutions and extended-release tablets and capsules Absorption by route of exposure: Ascorbic acid is readily absorbed after oral administration but the proportion does decrease with the dose. GI absorption of ascorbic acid may be reduced in patients with diarrhea or GI diseases. Distribution by route of exposure: Normal plasma concentrations of ascorbic acid are about 10 to 20 ug/mL. Total body stores of ascorbic acid have been estimated to be about 1.5 g with about a 30 to 45 mg daily turnover. Plasma concentrations of ascorbic acid rise as the dose ingested is increased until a plateau is reached with doses of about 90 to 150 mg daily. Ascorbic acid becomes widely distributed in body tissues with large concentrations found in the liver, leukocytes, platelets, glandular tissues, and the lens of the eye. In the plasma about 25% of the ascorbic acid is bound to proteins. Ascorbic acid crosses the placenta; cord blood concentration are generally 2 to 4 times the concentration in maternal blood. Ascorbic acid is distributed into milk. In nursing mothers on a normal diet the milk contains 40 to 70 ug/mL of the vitamin. Biological half-life by route of exposure: The plasma half-life is reported to be 16 days in humans. This is different in people who have excess levels of vitamin C where the half-life is 3.4 hours. Metabolism: Ascorbic acid is reversibly oxidized to dehydroascorbic acid in the body. This reaction, which proceeds by removal of the hydrogen from the enediol group of ascorbic acid, is part of the hydrogen transfer system. The two forms found in body fluids are physiologically active. Some ascorbic acid is metabolized to inactive compounds including ascorbic acid-2-sulfate and oxalic acid. Elimination by route of exposure: The renal threshold for ascorbic acid is approximately 14 ug/mL, but this level varies among individuals. When the body is saturated with ascorbic acid and blood concentrations exceed the threshold, unchanged ascorbic acid is excreted in the urine. When tissue saturation and blood concentrations of ascorbic acid are low, administration of the vitamin results in little or no urinary excretion of ascorbic acid. Inactive metabolites of ascorbic acid such as ascorbic acid-2-sulfate and oxalic acid are excreted in the urine. Ascorbic acid is also excreted in the bile but there is no evidence for enterohepatic circulation. Pharmacology and toxicology: Mode of action: Toxicodynamics: Hyperoxaluria may result after administration of ascorbic acid. Ascorbic acid may cause acidification of the urine, occasionally leading to precipitation of urate, cystine, or oxalate stones, or other drugs in the urinary tract. Urinary calcium may increase, and urinary sodium may decrease. Ascorbic acid reportedly may affect glycogenolysis and may be diabetogenic but this is controversial. Pharmacodynamics: In humans, an exogenous source of ascorbic acid is required for collagen formation and tissue repair. Vitamin C is a co-factor in many biological processes including the conversion of dopamine to noradrenaline, in the hydroxylation steps in the synthesis of adrenal steroid hormones, in tyrosine metabolism, in the conversion of folic acid to folinic acid, in carbohydrate metabolism, in the synthesis of lipids and proteins, in iron metabolism, in resistance to infection, and in cellular respiration. Vitamin C may act as a free oxygen radical scavenger. Toxicity: Human data: Adults: Diarrhea may occur after oral dosage of large amounts of ascorbic acid. Interactions: Concurrent administration of more than 200 mg of ascorbic acid per 300 mg of elemental iron increases absorption of iron from the GI tract. Increased urinary excretion of ascorbic acid and decreased excretion of aspirin occur when the drugs are administered concurrently. Ascorbic acid increases the apparent half-life of paracetamol. Interference with anticoagulant therapy has been reported. Carcinogenicity: It has been reported that there is no evidence of carcinogenicity. Some studies suggest that vitamin C may amplify the carcinogenic effect of other agents. L-ascorbic acid increases the oral carcinoma size induced by dimethylbenz(a)anthracene. Also, butylated hydroxyanisole induced forestomach carcinogenesis in rats. Teratogenicity: There is no evidence of teratogenicity. Mutagenicity: Ascorbic acid is reported to increase the rate of mutagenesis in cultured cells but this only occurs in cultures with elevated levels of Cu(2+) or Fe(2+). This effect may be due to the ascorbate induced generation of oxygen-derived free radicals. However, there is no evidence of ascorbate induced mutagenesis in vivo.
参考文献:M Chen, V Vijay, Q Shi, Z Liu, H Fang, W Tong. 用于研究药物诱导肝损伤的FDA批准药物标签,药物发现今日,16(15-16):697-703, 2011. PMID:21624500 DOI:10.1016/j.drudis.2011.05.007
M Chen, A Suzuki, S Thakkar, K Yu, C Hu, W Tong. DILIrank:按在人类中发展药物诱导肝损伤风险排名的最大参考药物清单。药物发现今日2016, 21(4): 648-653. PMID:26948801 DOI:10.1016/j.drudis.2016.02.015
References:M Chen, V Vijay, Q Shi, Z Liu, H Fang, W Tong. FDA-Approved Drug Labeling for the Study of Drug-Induced Liver Injury, Drug Discovery Today, 16(15-16):697-703, 2011. PMID:21624500 DOI:10.1016/j.drudis.2011.05.007
M Chen, A Suzuki, S Thakkar, K Yu, C Hu, W Tong. DILIrank: the largest reference drug list ranked by the risk for developing drug-induced liver injury in humans. Drug Discov Today 2016, 21(4): 648-653. PMID:26948801 DOI:10.1016/j.drudis.2016.02.015
Ascorbic acid is readily absorbed from the gastrointestinal tract and is widely distributed in the body tissues. Plasma concentrations of ascorbic acid rise as the dose ingested is increased until a plateau is reached with doses of about 90 to 150 mg daily. Body stores of ascorbic acid in health are about 1.5 g although more may be stored at intakes above 200 mg daily. The concentration is higher in leucocytes and platelets than in erythrocytes and plasma. In deficiency states the concentration in leucocytes declines later and at a slower rate, and has been considered to be a better criterion for the evaluation of deficiency than the concentration in plasma.
Ascorbic acid is reversibly oxidized to dehydroascorbic acid; some is metabolized to ascorbate-2-sulfate, which is inactive, and oxalic acid which are excreted in the urine. Ascorbic acid in excess of the body's needs is also rapidly eliminated unchanged in the urine; this generally occurs with intakes exceeding 100 mg daily.
来源:Hazardous Substances Data Bank (HSDB)
吸收、分配和排泄
抗坏血酸可穿过胎盘并分布到母乳中。它可以通过血液透析被清除。
Ascorbic acid crosses the placenta and is distributed into breast milk. It is removed by hemodialysis.
The renal threshold for ascorbic acid is approx 14 ug/mL, but this level varies among individuals. When the body is saturated with ascorbic acid and blood concentrations exceed the threshold, unchanged ascorbic acid is excreted in the urine. When tissue saturation and blood concentrations of ascorbic acid are low, administration of the vitamin results in little or no urinary excretion of ascorbic acid. Inactive metabolites of ascorbic acid such as ascorbic acid-2-sulfate and oxalic acid are excreted in the urine ... Ascorbic acid is also excreted in the bile but there is no evidence for enterohepatic circulation ...
Zur Kenntnis der D-,L-和DL-Erythron-undThreonsäure-内酯
摘要:
杜邦(Durch oxydativen)Abbau von D-核糖,L-阿拉伯糖,D-木糖和L-Ascorbinsäure位于碱溶液中Lösungmit Sauerstoff nach Spengler和Pfannenstiel wurden死于D- und L-Erythron-和Threonsäurenhergestellt。模具4中的Säurenwurden可用于内酯和苯酰肼,也可用于澳大利亚。Antipoden die ebenfalls kristallisierten DL-内酯hergestellt。死于D-和DL-Threonsäure-内酯Wurden erstmals beschrieben。
C–H Arylation of Heterocyclic <i>N</i>-Oxides Through <i>in Situ</i> Diazotisation Of Anilines without Added Promoters: A Green And Selective Coupling Process
作者:Aymeric P. Colleville、Richard A. J. Horan、Sandrine Olazabal、Nicholas C. O. Tomkinson
DOI:10.1021/acs.oprd.6b00117
日期:2016.7.15
A green and selective method for the generation of biaryl compounds through C–H arylation of heterocyclicN-oxides, in which the addition of ascorbic acid as a promoter is not required for either the generation of an aryldiazonium species or the subsequent arylation, is presented. Reaction conditions were optimized through multivariate data analysis, including orthogonal projections to latent structures
New methods and intermediates are discussed for the stereospecific synthesis of oxazinone compounds.
讨论了用于氧杂环酮化合物立体特异合成的新方法和中间体。
N-alkylpolyhydroxyamine salts of polyunsaturated fatty acids
申请人:Scotia Holdings PLC
公开号:US05990164A1
公开(公告)日:1999-11-23
An N-alkylpolyhydroxyamine salt of an n-6 or n-3 essential fatty acid (EFA) that is beyond the 6-desaturation step, or of any polyunsaturated fatty acid, other than those belonging to the n-6 and n-3 series, having 16 to 26 carbon atoms and up to six double bonds, the double bonds being in the cis or trans configuration, the salt being formed with the fatty acid either as such or in the form of a covalent derivative, through the carboxyl group, of a bifunctional compound itself having a free acid function.
[EN] NOVEL N-SUBSTITUTED DIHYDROBENZOTHIEPINO, DIHYDROBENZOXEPINO AND TETRAHYDRO BENZOCYCLOHEPTA INDOLES AS SELECTIVE ESTROGEN RECEPTOR MODULATORS<br/>[FR] NOUVEAUX DIHYDROBENZOTHIEPINO, DIHYDROBENZOXEPINO ET TETRAHYDRO BENZOCYCLOHEPTA INDOLES N-SUBSTITUES UTILISES EN TANT QUE MODULATEURS DU RECEPTEUR DES OESTROGENES
申请人:COUNCIL SCIENT IND RES
公开号:WO2005094833A1
公开(公告)日:2005-10-13
The invention provides a novel class of N-substituted dihydrobenzothiepino, dihydrobenzoxepino and tetrahydro benzocyclohepta indoles of Formula (I) and their pharmaceutically acceptable salts, and methods for of synthesizing these compounds. The invention further comprises pharmaceutical compositions and methods of use for these compounds for the treatment of estrogen related diseases or disorders.
catalytic condensation of carboxylic acids with equimolar amounts of alcohols is the most desirable. Although several highly active dehydration catalysts have been reported, more efficient alternatives are still strongly needed because the dehydrative esterification of tertiary alcohols, phenols, acid-sensitive alcohols, amino acids, and hardly soluble alcohols has never proceeded satisfactorily. Here